Limited Edition of 500 Pieces. U-Boat Watch Chimera Chronograph Green Steel Limited Edition 8528. The distinguishing feature of the U-Boat watches Chimera collection is the iconic case with its striking crown cap and pushers. These watches have a strong personality and embody Italos passion for Vintage Culture. With peerless clarity of design, Chimera has a profoundly clean appearance and a very masculine character. The bezel and case back are locked together by external tubing and a customized key that ensures total waterproofing. Five screws hold the bezel, case band and case back firmly together and the oversized crown cap for easy handling is secured to the carrure.